Physiological response of two peanut rhizobia strains to acid pH

TANIA TAURIAN, STELLA CASTRO AND ADRIANA FABRA

SYMBIOSIS

Balaban Publishers

Año: 1998 vol. 24 p. 327 - 336

0334-5114

Abstract Soil acidity is a stress factor that negatively affects the persistence of Rhizobium strains and the nodulation and nitrogen fixation in legumes. To identify peanut symbiont acid-tolerant strains we tested the ability of Bradyrhizobium USDA 3187 and Bradyrhizobium   sp. TT 001 (isolated from nodules of peanut) to grow at pH 5 in unbuffered broth medium. Only Bradyrhizobium sp. TT 001 grew at this pH and tolerance to this condition was not related with the synthesis of polyamines, lipopolysaccharide or with the production of extracellular polysaccharides. Cells of TT 001 were markedly resistant to the effects of crystla violet and was not affected by pH 5. These result suggest that the outer membrane structure could be involved in pH tolerance.